Novel crosslinker for chitosan microcapsules fabrication and properties evaluation.

What is it about?

This work is about evaluating the properties of bio-based chitosan microcapsules cross-linked with a novel cross-linking agent formulated with a mixture of oxalic acid and sodium phosphate dibasic heptahydrate. For the first time, chitosan was crosslinked with a mixture of oxalic acid and sodium phosphate dibasic heptahydrate, through the simple technique of electrospraying. The fabrication method is a simple one-step process where dissolved chitosan droplets form spheres immediately upon interaction with the cross-linking agent. The cross-linker provides sites that are anionic for the cationic chitosan to interact with electrostatically, forming and cross-linking the capsules. Tripolyphosphate is a well-known anionic cross-linker for chitosan that has such instant interaction with chitosan. It is polyanionic and has been predominantly used for the fabrication of physically cross-linked chitosan microcapsules using electrospraying technique. In this work, we reported another cross-linker that can serve the same purpose of forming and cross-linking chitosan microcapsules and the properties of the formed microcapsules.

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Photo by CDC on Unsplash

Photo by CDC on Unsplash

Why is it important?

Micro- and nanocapsules are important materials in fields like pharmaceutical, chemical, environmental, biomedical, materials science, food, and textile industries. They are extensively used in various applications including drug delivery, water treatment, nutrient/protein encapsulation, and coatings. Chitosan is an important natural biopolymer for fabricating these micro-/nanocontainers. Chitosan requires cross-linking to form microcapsules and impart important characteristics such as good mechanical strength, and thermal and chemical stability. Among several methods for fabricating chitosan microcapsules, the electrospraying technique mainly accommodates the use of tripolyphosphate for cross-linking chitosan. In this present work, we reported a novel cross-linker (OxPh) for fabricating and cross-linking chitosan micro-nanocapsules. Just like tripolyphosphate, this crosslinker is another desirable crosslinker for chitosan that is mild, biocompatible, non-toxic, and suitable for different fabrication methods including electrospraying. Evaluation of the properties of the cross-linked chitosan microcapsules indicated they possessed superior properties compared to those cross-linked with tripolyphosphate. This work is a welcomed breakthrough for industries that utilize nano-and microcapsules made from natural biopolymers like chitosan and require biobased cross-linker for the fabrication process. This novel cross-linker serves both as a complement and alternative for tripolyphosphate.

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